"On behalf of Sinn Fein I offer my sincere condolences to the victims and the families of those killed and injured and to the people of London," he said.No doubt some will think that time moves on, and peace has come, and such a message is entirely appropriate, although those who remember the deaths and awful injuries of 30 years ago may perhaps take a different view.. But it was not for want of trying.On 15 March 1976, 36-year-old Vincent Kelly set out to do just that. Just before the afternoon rush hour he boarded a train on what was then the Metropolitan Line (now the Hammersmith and City Line) at Stepney Green in the East End, carrying a bomb in a duffel bag. He intended to detonate it at Liverpool Street or another of the busy stations in the city centre. But he got on the wrong train, boarding one that was heading out of town.

He realised his mistake when the train came out above ground at Plaistow, where he got off and boarded an inbound train on the opposite platform. But by now the fuse on his bomb was running down and just as the train pulled out of West Ham station it went off, injuring but not incapacitating him. Kelly jumped off the train pursued by the driver and the guard: he shot them both, killing the former, Julius Stephen. When he was finally cornered by the police he turned the gun on himself.Had Kelly succeeded, he might well have wreaked carnage similar to yesterday's devastation between Russell Square and King's Cross But even then, the capital would have continued its life.

Don't let's tempt fate now, but London is probably just too big, too multi-faceted and too resilient to bring to its knees with a terror bombing campaign. Only a year before, the IRA had attacked the nearby Baltic Exchange building with a similar-sized bomb.The one London outrage the Provos did not manage to carry out was the one that gave yesterday's events their peculiarly grim horror - exploding a bomb on a London Underground train between stations. The Provos failed, although they tried hard enough.Yesterday Gerry Adams, president of Sinn Fein, said he had sent a message of sympathy and solidarity to Tony Blair and to London's Mayor, Ken Livingstone. The campaign reached its height in the winter of 1975-76 with the activities of four men who became known as the Balcombe Street gang - Harry Duggan, Martin O'Connell, Edward Butler and Hugh Doherty - who specialised in tossing bombs into crowded London restaurants. They killed several people before they were caught after a siege at a flat in Balcombe Street, Marylebone, where they had taken refuge.The blast that probably did the most damage to the capital's physical structures was towards the end of the campaign when the Provos attacked Bishopsgate at the heart of the City of London with a one-ton fertiliser bomb in a tipper truck.